This invention relates to a method of treating the surface of titanium or a titanium alloy (hereinafter titanium or a titanium alloy is simply referred to as a titanium alloy) to obtain a titanium alloy that can be used in parts sliding with other types of metals.
In general, various types of metal materials are used, for example, in engine parts for a vehicle. Heretofore, some of these engine parts have been made from titanium alloys which are smaller in specific gravity than steel materials, thereby reducing the weight of the entire engine. However, when parts made of titanium alloys which are not processed by a special surface treatment are used in parts sliding with other types of metals, the titanium alloy parts tend to cause burning with other metals or undergo considerable abrasion. In order to prevent this, titanium alloy parts have been surface treated by nitriding, cementation, or plating.
However, when a titanium alloy part is surface treated such as by nitriding, hardness of the part is remarkably increased, which tends to increase abrasion of a metal part sliding with the titanium alloy part. When the surface of a titanium alloy part is plated, the coating layer tends to peel during sliding with partner metal parts, thus posing a reliability problem. Therefore, development of a low-cost and reliable surface treatment method has been in demand.